1. Technical Field
The present invention pertains to medical devices employing disposable medical items. In particular, the present invention pertains to ensuring operation of medical devices with sterile disposable items to prevent contamination and injury to a patient.
2. Discussion of Related Art
The maintenance of sterile conditions during performance of medical procedures is crucial to prevent infection and injury to a patient. Accordingly, medical items utilized within a medical procedure are typically sterilized prior to performance of the procedure and maintained within a sterile field to ensure sterility. Various medical items maybe disposable in order to reduce the amount of sterilization. These items are typically limited to a single use, thereby requiring a new sterile item for each procedure. For example, a disposable surgical drape maybe employed to serve as a container and provide a sterile field for a sterile medium within a basin of a thermal treatment system. The drape is discarded after a single use and replaced with a new sterile drape for each procedure. Further, disposable IV fluid cassettes or delivery sets may be employed during infusion of fluids into a patient. These items are similarly discarded after a single use and replaced for each procedure. Although disposable medical items are intended for a single use, there is no assurance that carelessness will not result in operation of medical devices with a prior used or non-sterile item, thereby contaminating medical procedures and risking serious injury to patients.
The related art has attempted to overcome the aforementioned problem by providing various mechanisms to determine prior use and/or detect conditions compromising sterility of medical items used with medical devices. For example, U.S. Pat. No. 5,040,699 (Gangemi) discloses a fluid compounding system wherein solution dispensing containers dispense respective fluids into a solution receiving bag via pumps under microprocessor control. The receiving bags include a bar code that is read by a bar code wand electrically connected to the system. The bar code is utilized to identify receiving bags previously used in order to prevent those receiving bags from being reused.
U.S. Pat. No. 5,524,643 (Faries, Jr. et al) discloses a method and apparatus directed toward preventing damage to drapes and heating and cooling mechanisms of a thermal treatment apparatus, and to preserving the sterile field when using such apparatus. A surgical drape is combined with a sensor, preferably attached to the drape, to detect the presence of liquid within a drape container conforming to a heating/cooling thermal treatment apparatus basin. An alternative embodiment employs sensors at opposite surfaces of the drape to measure conductance and, thereby, leakage through the drape. A microprocessor of each embodiment receives a signal representing, for example, an electrical conductance measurement and determines the presence of liquid and/or a leak. If liquid is not present or a leak is determined to exist (e.g., a drape leak enables contamination of the drape and/or liquid), the microprocessor disables a temperature controller for the basin.
U.S. Pat. No. 5,653,938 (Faries, Jr. et al) discloses an apparatus for ensuring sterility of a drape for use on surgical equipment by employing bar codes and a microprocessor. When a drape containing a bar code is placed on the corresponding surgical equipment, a bar code reader ascertains the bar code on the drape. A microprocessor receives the bar code and determines whether the bar code has been previously written to memory indicating drape prior use. If the bar code is not present, the current bar code of the drape is written into memory, and subsequent operation of the surgical equipment commences. If the bar code is present, the microprocessor prevents the surgical equipment from operating.
The related art systems described above may stand some improvement. In particular, the Gangemi and Faries Jr. et al (U.S. Pat. No. 5,653,938) systems employ bar codes to identify and determine prior item use. Thus, substantial logistics are required to ensure that a proper bar code is associated with each item to prevent erroneous prior use determinations. Further, storage of numerous item bar codes for later comparison tends to exhaust system memory and typically requires removal of bar codes or installment of additional memory. This provides system users with additional tasks, thereby increasing system operating costs and complexity. The Faries, Jr. et al sensor drape system (U.S. Pat. No. 5,524,643) detects a non-sterile drape by determining the presence of leaks within that drape. Thus, this system is limited to detecting particular circumstances or conditions that tend to contaminate drapes or render drapes non-sterile.